Summary: 1. In-house serologic and genetic assays and Taqman probes are being developed for HIV-1 group O and non clade B subtypes. An in-house HIV group O ELISA and primers and probes for HIV group O and M has been developed. The probes will be used to generate microarray based assays for viral genotype. Oligo Chips are being developed to detect all known HIV group M subtypes, group O subtypes. In addition probes that are subtype specific are also under development. These assays will serve as tools in molecular epidemiologic studies to determine prevalence of non clade B strains particularly HIV-1 group O in endemic areas. We have recently initiated a study to study molecular evolution of HIV in Camerooon a region which harbors several subtypes. In these studies we will be characterizing various strains from specimens collected in Cameroon in order to identify new strains. WE have begun studies to investigate the diagnostic significance of strain diversity by testing sera using FDA licensed antibody and nucleic acid tests. We will also compare the performance of various direct viral marker assays such as PERT, RT-PCR, and p24 assays for their ability to detect viral variants and HIV in the early phase of infection. 2. Panels are being developed for the quantitation of RNA of HIV-1 subtypes. Virus isolates from each subtype have been sequenced to verify the subtype. These isolates are being quantitated in a collaborative study. An HIV-2 panel is also under development.